U.S. patent number 6,505,948 [Application Number 09/818,630] was granted by the patent office on 2003-01-14 for method of modifying the spectral distribution of high-intensity ultraviolet lamps.
This patent grant is currently assigned to Fusion UV Systems, Inc.. Invention is credited to Miodrag Cekic, Mark W. Ruckman.
United States Patent |
6,505,948 |
Cekic , et al. |
January 14, 2003 |
Method of modifying the spectral distribution of high-intensity
ultraviolet lamps
Abstract
The invention is a microwave excited light source. A microwave
excited light source in accordance with the invention includes a
microwave source (100) which produces microwaves; a microwave
excited light bulb (106), coupled to the microwave source, which
produces an output spectrum 108 and operates within a first
temperature range when producing the output spectrum with at least
one frequency range of the output spectrum having a power level
below a desired level; and an optical component (20, 40, 60, 70,
110, 116 and 118), spaced from the light bulb which operates in a
second temperature range below the first temperature range, having
at least one phosphor (112) which is excited by another frequency
range of the output spectrum, the at least one phosphor in response
to the another frequency range outputs light in the at least one
portion which increases the power level to the desired level.
Inventors: |
Cekic; Miodrag (Bethesda,
MD), Ruckman; Mark W. (Montgomery Village, MD) |
Assignee: |
Fusion UV Systems, Inc.
(Gaithersburg, MD)
|
Family
ID: |
25226001 |
Appl.
No.: |
09/818,630 |
Filed: |
March 28, 2001 |
Current U.S.
Class: |
362/84; 250/504R;
315/344; 315/39; 362/293 |
Current CPC
Class: |
H05B
41/24 (20130101) |
Current International
Class: |
F21V
9/16 (20060101); F21V 9/00 (20060101); H01J
65/04 (20060101); H05B 41/24 (20060101); F21V
009/16 (); H01J 065/04 () |
Field of
Search: |
;315/39,111.21,111.51,246,248,267,344 ;313/231.31,231.61,483,493
;250/54R ;362/84,260,296,293 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
|
|
|
|
|
|
|
5442383 |
|
Apr 1979 |
|
JP |
|
5512143 |
|
Jan 1980 |
|
JP |
|
401264103 |
|
Oct 1989 |
|
JP |
|
0999106 |
|
Apr 1997 |
|
JP |
|
10260349 |
|
Sep 1998 |
|
JP |
|
216459 |
|
Jan 1999 |
|
JP |
|
Primary Examiner: Cariaso; Alan
Attorney, Agent or Firm: Antonelli, Terry, Stout &
Kraus, LLP
Claims
What is claimed is:
1. A microwave excited light source comprising: a microwave source
which produces microwaves; a microwave excited light bulb, coupled
to the microwave source, which produces an output spectrum and
operates within a first temperature range when producing the output
spectrum with at least one frequency range of the output spectrum
having a power level below a desired level; and an optical
component, spaced from the light bulb which operates in a second
temperature range below the first temperature range, having at
least one phosphor which is excited by another frequency range of
the output spectrum, the at least one phosphor in response to the
another frequency range outputs light in the at least one frequency
range which increases the power level to the desired level; and
wherein the one and the another range of the spectrum are UV.
2. A microwave excited light source in accordance with claim 1
wherein: the optical component is an optical filter through which
the output spectrum passes.
3. A microwave excited light source in accordance with claim 1
wherein: the optical component is a reflector which reflects the
output spectrum.
4. A microwave excited light source in accordance with claim 1
wherein: the optical component is a window through which the output
spectrum passes.
5. A microwave excited light source in accordance with claim 1
wherein: the at least one phosphor is operational within the second
temperature range and rendered non-operational at the first
temperature range.
6. A microwave excited light source in accordance with claim 2
wherein: the at least one phosphor is operational within the second
temperature range and rendered non-operational at the first
temperature range.
7. A microwave excited light source in accordance with claim 3
wherein: the at least one phosphor is operational within the second
temperature range and rendered non-operational at the first
temperature range.
8. A microwave excited light source in accordance with claim 4
wherein: the at least one phosphor is operational within the second
temperature range and rendered non-operational at the first
temperature range.
9. A microwave excited UV light source comprising: a microwave
source which produces microwaves; a microwave excited UV light
bulb, coupled to the microwave source, which produces an UV output
spectrum representative of UV light produced by the sun and having
an operation temperature range when producing the UV output
spectrum with at least one frequency range of the UV output
spectrum in a first UV wavelength range having a power level below
a desired level; an optical component, spaced from the light bulb,
which operates in a second temperature range below the first
temperature range having at least one phosphor which is excited by
at least one frequency range of the UV output spectrum within a
second UV wavelength range shorter than the first UV wavelength
range, the at least one phosphor in response to the at least one
frequency range within the second UV wavelength range outputting UV
light within the at least one frequency range of the first UV
wavelength range which increases the power level to the desired
level; and the at least one phosphor is operational within the
second temperature range and is rendered non-operational at the
first temperature range.
10. A microwave excited UV light source in accordance with claim 9
wherein: the second UV wavelength range has a maximum wavelength of
approximately 300 nm; and the first UV wavelength range is between
approximately 300-450 nm.
11. A microwave excited UV light source in accordance with claim 10
wherein: the first UV wavelength range is between approximately
300-350 nm.
12. A microwave excited UV light source in accordance with claim 11
wherein: the second UV wavelength range is approximately centered
about 250 nm.
13. A microwave excited UV light source in accordance with claim 9
wherein: the at least one phosphor is Ca.sub.3 (PO.sub.4).sub.2
:Tl.
14. A microwave excited UV light source in accordance with claim 9
wherein: the at least one phosphor is (Ca.sub.0.9 Zn.sub.0.1).sub.3
(PO.sub.4).sub.2 :Tl.
15. A microwave excited UV light source in accordance with claim 13
wherein: the at least one phosphor has 3-4 mol % Tl.
16. A microwave excited UV light source in accordance with claim 14
wherein: the at least one phosphor has 3-4 mol % Tl.
17. A microwave excited UV light source in accordance with claim 9
wherein: the at least one phosphor is Sr.sub.2 MgSi.sub.2 O.sub.7
:Pb.
18. A microwave excited UV light source in accordance with claim 9
wherein: the at least one phosphor is BaSi.sub.2 O.sub.5 : Pb.
19. A microwave excited UV light source in accordance with claim 9
wherein: the at least one phosphor is (Ba.sub.1.6
Sr.sub.0.4)Si.sub.2 O.sub.7 :Pb.
20. A microwave excited UV light source in accordance with claim 9
wherein: the at least one phosphor is Ba.sub.2 ZnSi.sub.2 O.sub.7
:Pb.
21. A microwave excited UV light source in accordance with claim 9
wherein: the at least one phosphor is SrB.sub.4 O.sub.7 F:Eu.
22. A microwave excited UV light source in accordance with claim 9
wherein: the optical component is a reflector which reflects the UV
output spectrum.
23. A microwave excited UV light source in accordance with claim 10
wherein: the optical component is a reflector which reflects the UV
output spectrum.
24. A microwave excited UV light source in accordance with claim 11
wherein: the optical component is a reflector which reflects the UV
output spectrum.
25. A microwave excited UV light source in accordance with claim 12
wherein: the optical component is a reflector which reflects the UV
output spectrum.
26. A microwave excited UV light source in accordance with claim 13
wherein: the optical component is a reflector which reflects the UV
output spectrum.
27. A microwave excited UV light source in accordance with claim 14
wherein: the optical component is a reflector which reflects the UV
output spectrum.
28. A microwave excited UV light source in accordance with claim 15
wherein: the optical component is a reflector which reflects the UV
output spectrum.
29. A microwave excited UV light source in accordance with claim 16
wherein: the optical component is a reflector which reflects the UV
output spectrum.
30. A microwave excited UV light source in accordance with claim 17
wherein: the optical component is a reflector which reflects the UV
output spectrum.
31. A microwave excited UV light source in accordance with claim 18
wherein: the optical component is a reflector which reflects the UV
output spectrum.
32. A microwave excited UV light source in accordance with claim 19
wherein: the optical component is a reflector which reflects the UV
output spectrum.
33. A microwave excited UV light source in accordance with claim 20
wherein: the optical component is a reflector which reflects the UV
output spectrum.
34. A microwave excited UV light source in accordance with claim 9
wherein: the optical component is an optical filter through which
the UV output spectrum passes.
35. A microwave excited UV light source in accordance with claim 10
wherein: the optical component is an optical filter through which
the UV output spectrum passes.
36. A microwave excited UV light source in accordance with claim 11
wherein: the optical component is an optical filter through which
the UV output spectrum passes.
37. A microwave excited UV light source in accordance with claim 12
wherein: the optical component is an optical filter through which
the UV output spectrum passes.
38. A microwave excited UV light source in accordance with claim 13
wherein: the optical component is an optical filter through which
the UV output spectrum passes.
39. A microwave excited UV light source in accordance with claim 14
wherein: the optical component is an optical filter through which
the UV output spectrum passes.
40. A microwave excited UV light source in accordance with claim 15
wherein: the optical component is an optical filter through which
the UV output spectrum passes.
41. A microwave excited UV light source in accordance with claim 16
wherein: the optical component is an optical filter through which
the UV output spectrum passes.
42. A microwave excited UV light source in accordance with claim 17
wherein: the optical component is an optical filter through which
the UV output spectrum passes.
43. A microwave excited UV light source in accordance with claim 18
wherein: the optical component is an optical filter through which
the UV output spectrum passes.
44. A microwave excited UV light source in accordance with claim 19
wherein: the optical component is an optical filter through which
the UV output spectrum passes.
45. A microwave excited UV light source in accordance with claim 20
wherein: the optical component is an optical filter through which
the UV output spectrum passes.
46. A microwave excited UV light source in accordance with claim 9
wherein: the optical component is a window through which the UV
output spectrum passes.
47. A microwave excited UV light source in accordance with claim 10
wherein: the optical component is a window through which the UV
output spectrum passes.
48. A microwave excited UV light source in accordance with claim 11
wherein: the optical component is a window through which the UV
output spectrum passes.
49. A microwave excited UV light source in accordance with claim 12
wherein: the optical component is a window through which the UV
output spectrum passes.
50. A microwave excited UV light source in accordance with claim 13
wherein: the optical component is a window through which the UV
output spectrum passes.
51. A microwave excited UV light source in accordance with claim 14
wherein: the optical component is a window through which the UV
output spectrum passes.
52. A microwave excited UV light source in accordance with claim 15
wherein: the optical component is a window through which the UV
output spectrum passes.
53. A microwave excited UV light source in accordance with claim 16
wherein: the optical component is a window through which the UV
output spectrum passes.
54. A microwave excited UV light source in accordance with claim 17
wherein: the optical component is a window through which the UV
output spectrum passes.
55. A microwave excited UV light source in accordance with claim 18
wherein: the optical component is a window through which the UV
output spectrum passes.
56. A microwave excited UV light source in accordance with claim 19
wherein: the optical component is a window through which the UV
output spectrum passes.
57. A microwave excited UV light source in accordance with claim 20
wherein: the optical component is a window through which the UV
output spectrum passes.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to microwave excited light sources
which utilize a phosphor(s) or phosphor containing component(s)
coated on or within components external to a microwave excited
light bulb therein to produce a desired light output spectrum
augmented by the light output spectrum produced by the phosphor(s)
or phosphor containing component(s).
2. Description of the Prior Art
The Assignee of the present invention sells microwave excited light
sources using light bulbs having a medium to high filling pressure
and high applied microwave power which produce high radiance in the
UV frequency range. Bulbs of a one to ten-inch nominal length are
powered with a range of microwave power from 1 kW to 10 kW. These
UV light sources have nominal power loads ranging from 100
watts/inch to 1000 watts/inch. The Assignee's microwave excited UV
light sources convert the input electrical power to a UV light
output with an efficiency of between 10-35%. Microwave excited UV
light sources have the advantage of producing high output power and
a frequency stable spectrum from more than 3,000 hours of
operation.
FIG. 1 illustrates a prior art UV spectrum produced by the
Assignee's microwave excited UV light sources. As is apparent in
the UV range, there is a substantial drop off in output power
between 300-350 nm. The spectrum illustrated in FIG. 1 is provided
upon request to customers of the Assignee's microwave-powered
electrodeless lamps to enable the customers to best understand the
frequency ranges present in the UV light output used for the
customers' UV light applications.
The aging of surfaces, coatings, etc., with irradiation from
between 290-420 nm, is conventionally performed to determine the
properties of the surface coatings in response to extended exposure
to solar radiation. The higher the irradiance of the UV light, the
more rapid an aging study may be completed. The spectrum of a
commercial solar lamp has rising UV power emission in the spectral
range between 300-350 nm. The prior art spectrum illustrated in
FIG. 1 has a total maximum emission at about 330 nm. The Assignee's
microwave excited UV light sources can produce a much higher power
irradiance than a commercial solar lamp and more efficiently
convert the input power into light than a commercial solar lamp.
However, the UV spectral distribution of the Assignee's microwave
excited UV light sources is not most suitable to perform solar
aging studies in view of the large drop off in the potentially
important wavelength range between 300-350 nm.
A need exists for a high efficiency, high power solar irradiation
light source which simulates the UV light spectrum produced by the
sun as well or better than standard solar lamps so as to permit
accelerated solarization studies of a wide variety of surfaces,
paints, coatings, etc.
In a fluorescent lamp, a phosphor placed on an inner wall of the
lamp downshifts the UV emission of a low-pressure mercury discharge
into the optical range. More than one phosphor or a phosphor with
more than one activator may be used to produce a desired color.
Phosphors that fluoresce in low power lamps in the ultraviolet
range between 295-400 nm produce UV-A, B or C emissions are used
for tanning and medical treatment.
Phosphors containing thallium, lead or europium activators in a
variety of host materials produce emissions which lie in the range
between 300-350 nm. However, such materials are temperature
sensitive and their light conversion efficiency decreases with
temperature. The aforementioned properties restrict incorporation
of these phosphor materials into a bulb wall with a temperature
below 100.degree. C.
SUMMARY OF THE INVENTION
The present invention is a high efficiency, high intensity
microwave driven light source having a preferred application as a
UV light source. A light source in accordance with the invention
utilizes high power microwave excitation to produce UV light with
wavelengths which excite a phosphor(s) or phosphor(s) containing
components or compositions coated on or within optical components
external to the microwave excited light bulb. The phosphor(s) or
phosphor(s) containing components or compositions produce light
emissions in a desired frequency range(s) of the output spectrum
which is additive to the power level of the output spectrum in the
desired frequency range(s) produced by the microwave excited lamp
bulb to achieve a desired power output in the desired frequency
range(s) of or in the entire output spectrum. The downshifting
provided by UV phosphor(s) or UV phosphor(s) containing components
or compositions on surfaces of or within components of a
microwave-powered UV light source external to the light bulb,
whether on reflective surfaces, filters, windows, optics, or a
pellicle, separates temperature sensitive phosphor(s) or
phosphor(s) containing components or compositions from the high
temperature of the microwave excited bulb so that the microwave
powered light source can be operated at high power output with any
desired light spectrum at whatever temperature is required for
optimal operation. High intensity light produced by microwave
excited light bulbs prevents phosphors from being coated thereon in
view of their high output surface temperatures which may exceed
1,000.degree. C.
With the invention the spectral distribution of light produced by
microwave-powered light sources, which are optimized for other
purposes such as the efficiency of producing light from the input
electrical power, permits operation without having to introduce
additional chemical components or compounds, as dopants into the
bulb fill.
As used herein, a phosphor(s) includes a phosphor(s) alone or as
part of components or compositions containing a phosphor(s) which
phosphoresce to produce light in the visible or UV range. The
phosphors may be a surface coating on or within the optical
components external to the light bulb.
A microwave excited light source in accordance with the invention
includes a microwave source which produces microwaves; a microwave
excited lamp bulb, coupled to the microwave source, which produces
an output spectrum and operates within a first temperature range
when producing an output spectrum with at least one frequency range
of the output spectrum having a power level below a desired level;
and an optical component, spaced from the bulb which operates in a
second temperature range below the first temperature range, having
at least one phosphor which is excited by another frequency range
of the output spectrum, the at least one phosphor in response to
the another frequency range outputs light in the at least one
frequency range which increases the power level to the desired
level. The optical component may be a filter through which the
output spectrum passes. The optical component may be a reflector
which reflects the output spectrum. The optical component may be a
window through which the output spectrum passes. The at least one
phosphor may be operational within the second temperature range and
may be rendered non-operational at the first temperature range. The
one and the another frequency range of the spectrum may be in the
UV range.
The invention is a microwave excited UV light source including a
microwave excited UV lamp bulb, coupled to the microwave source,
which produces an UV output spectrum representative of UV light
produced by the sun and having an operation temperature range when
producing the UV output spectrum with at least one frequency range
of the UV output spectrum in a first UV wavelength range having a
power level below a desired level; an optical component, spaced
from the bulb, which operates in a second temperature range below
the first temperature range having at least one phosphor which is
excited by at least one frequency range of the UV output spectrum
within a second UV wavelength range shorter than the first UV
wavelength range, the at least one phosphor in response to the at
least one frequency range within the second UV wavelength range
outputting UV light within the at least one frequency range of the
first UV wavelength range which increases the power level to the
desired level; and the at least one phosphor is operational within
the second temperature range and is rendered non-operational at the
first temperature range. The second UV wavelength range may have a
maximum wavelength of approximately 300 nm; and the first UV
wavelength range may be between approximately 300-450 nm and
preferable, the first wavelength range may be between approximately
300-350 nm. The second wavelength range may be approximately
centered about 250 nm. The at least one phosphor may be Ca.sub.3
(PO.sub.4).sub.2 :Tl or (Ca.sub.0.9 Zn.sub.0.1).sub.3
(PO.sub.4).sub.2 :Tl and have 3-4 mol % Tl. The at least one
phosphor may be Sr.sub.2 MgSi.sub.2 O.sub.7 :Pb, BaSi.sub.2 O.sub.5
:Pb, Ba.sub.1.6 Sr.sub.0.4 Si.sub.2 O.sub.5 :Pb, Ba.sub.2
ZnSi.sub.2 O.sub.7 :Pb, or SrB.sub.4 O.sub.7 F:Eu. The optical
component may be a reflector which reflects the UV output spectrum,
a filter through which the UV output spectrum passes, or a window
through which the UV output spectrum passes.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 illustrates the prior art light output spectrum of a
microwave excited UV light source sold by the Assignee of the
present invention.
FIG. 2 illustrates a schematic of an embodiment of a microwave
excited light source in accordance with the invention.
FIG. 3 illustrates the emission spectrum of various phosphors or
phosphor containing components or compositions which may be used
with the microwave excited lamp source of the invention.
FIG. 4 illustrates another embodiment of the present invention.
FIG. 5 illustrates the output spectrum of a microwave excited UV
light source in accordance with the present invention which has
been modified from the standard output spectrum of FIG. 1 to
simulate solar radiation.
FIG. 6 illustrates another embodiment of the present invention.
FIG. 7 illustrates yet another embodiment of the present
invention.
Like reference numerals identify like parts throughout the
drawings.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
FIG. 2 illustrates an embodiment of the present invention. A
microwave excited high intensity light source 10 produces a high
power light spectrum which is enhanced externally beyond the light
source to boost the power of frequency components produced by a
microwave excited light bulb contained in the light source. The
invention has a preferred application of producing a UV spectrum
with a most preferred application being for the simulation of the
UV spectrum of natural sunlight for providing expedited aging
studies of surfaces, coatings, paints, films, etc. Microwave
excited light source 10 is of conventional construction which is
preferably a UV light source. The high intensity light source 10
includes a microwave source (not illustrated) which produces
microwaves; a microwave excited light bulb (not illustrated) to
which the microwaves are coupled by a microwave cavity (not
illustrated) in a conventional manner. The output light spectrum 12
is produced by emissions from the light bulb which operates within
a first temperature range. At least one frequency range of the
output light spectrum 12 has the radiance below a desired level. An
optical component, spaced from the bulb, operates in a second
temperature range, below the first temperature range, which has at
least one phosphor which is excited by at least one other frequency
range of the output light spectrum produced by the light bulb. The
at least one phosphor in response to the at least one other
frequency range of the output spectrum emits light in the at least
one frequency range having a power level below the desired level
which increases the power level to the desired level. The light 12
contains the higher energy in at least one other frequency range
which is in the UV range and is used to excite the at least one
phosphor on or within one or more surfaces of diverse components in
the microwave excited light source through which the light 12
passes as explained below.
The phosphors may be coated surfaces on or contained in the various
components exterior to the microwave excited bulb. One or more
components external from the light bulb contains or is coated with
a thin film or surface coating containing at least one phosphor on
at least one face which is excited by higher energy UV to produce
lower energy visible or UV light in the desired spectrum in which a
higher power level is desired. While the phosphor(s) are
illustrated as a surface coating in the form of "xxx", it should be
understood that the illustration is representative of the
phosphor(s) within the materials from which the optical components
external to the light bulb are made. At least one filter 20 may be
provided in the path of the light 12 which contains or is coated
with a thin film or surface coating of the at least one phosphor on
one or both sides as illustrated, which is excited by the higher
energy excitation UV spectrum to produce the lower energy emission
spectrum which may be either in the visible or UV range.
Additionally, optics 30 may contain or be coated on at least one,
and preferably on two faces, with a thin film or surface coating 40
containing the at least one phosphor which is excited by the higher
energy frequency range of the output light spectrum containing at
least one phosphor to emit light in a desired lower frequency range
to enhance the output light spectrum in a frequency range where
enhancement is desirable. Additionally, a window 50 containing the
phosphor(s) or having a thin film or surface coating 60 containing
the at least one phosphor, may be placed in the light 12. Finally,
a pellicel 70 containing the phosphor(s) or coated with a thin film
or a surface coating containing the at least one phosphor, may be
placed in the output light 12. A target 80 is illuminated by light
to which has been added additional light power in at least one
lower energy frequency range of the output spectrum which is not
present at a sufficient power level in the output light 12 produced
from the microwave excited light source 10. The resultant overall
spectrum reaching the target 80, which is preferably in the UV
range, has the desired power level across the desired light
spectrum. The target 80 may be a surface, a surface coating, paint
or a film, etc., which is to be illuminated with the light of the
desired power level in the desired optical spectrum such as, but
not limited to, UV light, which simulates natural sunlight to
perform expedited aging studies of the target which approximate the
effect of natural sunlight.
As illustrated, phosphors or phosphor containing components or
compositions are within or are coated on any one or more of the
surfaces of filters 20, the optics 30, the window 50 and the
pellicel 70 to enhance the output spectrum to the desired power
level.
FIG. 3 illustrates phosphors or phosphor containing materials or
compositions which may be used in the embodiment of FIG. 2 and the
embodiments of the invention described below in conjunction with
FIGS. 4, 6 and 7. The excitation frequency range for each phosphor
is at a shorter wavelength than the emission frequency range which
produces the increased power level in the one or more frequency
ranges of the output spectrum produced by the microwave excited
bulb which has a power level below a desired level.
For some of the phosphors, a range of excitation frequencies is
represented by a pair of numbers separated by a dash. For other
phosphors, a very narrow frequency range excitation in parenthesis,
such as 253.7 nm produced by mercury emission, is used as the
excitation frequency to produce a narrow peak emission output
frequency range also in parenthesis. Each of the phosphors in FIG.
3 is thermally stable when placed within the optical compounds or
coated on the surfaces of the optical components of the microwave
powered light source of the invention which are external to the
light bulb surface and produces emissions which enhance the UV
spectrum of FIG. 1.
Each phosphor may be excited with high intensity short wave UV
light to produce the enhanced power output in the range between
approximately 300-380 nm required to increase the light output
power present in the Assignee's commercial microwave-powered UV
lamps to permit expedited solar aging studies to be performed. Each
phosphor of FIG. 3 may be within or coated directly on exterior
surfaces external to the light bulb surface as described above
which are illuminated by the light emitted from the microwave
powered light source.
FIG. 4 illustrates a second embodiment of the present invention
utilizing a conventional microwave source 100 such as that present
in the Assignee's microwave powered UV lamps. The microwave source
100 produces microwaves 102 which are transmitted by a waveguide
103 to a microwave cavity 104 in which a high intensity microwave
excited bulb 106 is located which may produce either visible or UV
light. The output light 108, which has at least one frequency range
of the output spectrum of a deficient power level required for the
application of the embodiment, is incident on a reflector 110 of
conventional design containing or coated with a surface coating or
layer 112 containing the at least one phosphor such as, but not
limited to, those contained in FIG. 3. The output light 114 has an
increased power level in the at least one frequency range of the
output spectrum 100 as a result of the emissions produced by the
surface coating or layer 112. The power level of the output light
114, as a result of the emissions from the phosphor 112, is at the
desired output power level necessary for the application such as
enhanced solar aging studies.
FIG. 5 illustrates an output light spectrum of the embodiments of
the invention in FIGS. 2, 4, 6, and 7 when using (Ca.sub.0.9
Zn.sub.0.1).sub.3 (PO.sub.4).sub.2 :Tl. As illustrated, the dotted
line excitation spectrum 200 produced by (Ca.sub.0.9
Zn.sub.0.1).sub.3 (PO.sub.4).sub.2 :Tl is centered around 250 nm.
The resultant emission spectrum 202 peaks at around 330 nm. The
resultant cumulative spectrum, with enhanced irradiance between
300-380 nm, approximates the UV spectrum present in solar light,
which is desired to perform enhanced aging studies of surfaces,
coatings, paints, etc.
FIG. 6 illustrates another embodiment of the invention in which
only the reflector 110 is shown containing or including the
phosphor 112 coated on both sides of window 116 of the microwave
excited light source to produce output light with at least one
frequency range of the output spectrum 108 having been increased in
power level by the presence of the phosphor contained in the
components of or coated on one or more surfaces of the components
of the optical system 116.
FIG. 7 illustrates another embodiment of the invention in which the
phosphor 112 is coated on the surfaces of the optical system or is
within the components of the optical system 118 to produce output
light 114 with at least one frequency range of the output spectrum
108 having been increased in power level by the presence of the
phosphor 112 within the optical system.
While the invention has been described in terms of its preferred
embodiments, it should be understood that numerous modifications
may be made thereto without departing from the spirit and scope of
the invention. For example, the at least one phosphor, which
preferably produces output light in the UV spectrum for performing
enhanced aging studies, may be applied to enhance other spectra,
such as of the visible output spectrum, to produce high intensity
output light having a specifically selected spectrum of a high
power level which is not produced by microwave excitation of a bulb
alone. It is intended that all such modifications fall within the
scope of the appended claims.
* * * * *